Question

A frictionless pendulum is made with a bob of mass 19.7 kg. The bob is held at height = 0.934 meter above the bottom of its trajectory, and then pushed forward with an initial speed of 2.93 m/s. What amount of mechanical energy does the bob have when it reaches the bottom?
96 J

136 J

265 J

180 J

Answer 1

Answer:

265 J

Explanation:

$Energy=PE+KE=mgh+ 0.5mv^{2}$ where KE is kinetic energy, PE is potential energy, m is the mass of an object, v is the speed, h is the height and g is acceleration due to gravity.

Substituting 19.7 Kg for mass, 0.934 for h, 2.93 for v and 9.81 for g then

$Energy=19.7(9.81*0.934+0.5*2.93^{2})=265.063303\approx 265 J$